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It's TED, of course it has some idiocy.
At this point, I'm just waiting for you to read section II of my article and realize that I'm not interested in defending AWG here.

Originally Posted by Strange

You can't use a thought experiment where cooperation is specifically prevented as evidence that people will not cooperate under normal circumstances.

Are you seriously going to argue that zero-sum and negative-sum games do not exist in reality?

Originally Posted by Strange

How big a counterexample: the solar system, the entire universe? Clearly structures of any mass can exist and be larger than their Schwarzschild radius. If it were not the case, the universe would not exist.

What I was asking is whether you can think of a structure that scales up without collapsing. Neither of your examples, possibly barring the universe as a whole, achieves that.
Maybe that is an overly strong requirement, but I just don't see a civilization rebuilding itself from scratch every time they need to add another building or something. And even if they do, the incentives would be to keep the structure as close to the brink of collapse as possible, which isn't particularly stable either.

Originally Posted by Dave241

Hello FunBotan! I love talking about the Fermi Paradox, I find it fascinating. But before I comment on the details of what you propose, my biggest objection is that even if true this won't solve the Fermi Paradox. Your proposal concludes with "advanced enough civilizations will eventually collapse into a black hole". Is that about right?
Well, in order to get to that point, you first have to become incredibly advanced. As in, probably at least a Kardashev II civilization that is building Dyson Swarms, right? Sorry to say it but even if you did collapse the home system into a black hole you have not killed the civilization. They would have many habitats in the outer parts of the solar system which would survive. They would have ships en route to other colonies with people on board. They would have some very well established colonies around many of the nearby star systems, each with it's own Dyson Swarm. They would be in the process of establishing new colonies around more distant star systems. And all of this kind of activity would be both:
a) Visible to anyone with a telescope
b) Prevent the entire civilization from dying just because their home star system was destroyed in a terrible accident.
So before we even get into your proposal, I don't see it as a viable solution to the Fermi Paradox.

Yeah, I see where you're coming from. You assume civilizations use stars as they are as opposed to treating them as resources. I disagree with that.
Once a civilization gets hold of controlled nuclear fusion, stars already become obsolete. And that's far from the most efficient/advanced reactor theoretically possible. So it's much more likely advanced civilizations will disassemble stars and store them in some stable state as fuel, which is where the logic of my article comes in.

Originally Posted by Dave241

While I would agree that a system that is maximizing it's future actions is probably an intelligent system, I am with the others that are complaining that they can also think of intelligent systems (ie humans) NOT maximizing it's future freedom of actions.

Well, this is the same thing as with life. Although there might be organisms that do not reproduce, they will eventually be overwhelmed by those who do, so it's completely fair to include the ability to reproduce into the definition of an organism even if it isn't necessarily true for each and every specimen.
Similarly, an agent who aims to increase his freedom of action will eventually have all of it, so it doesn't matter what other agents do because their freedom of action is too small in comparison, and thus their decisions don't affect what happens to the civilization.

Are you seriously going to argue that zero-sum and negative-sum games do not exist in reality?

Stop posting non-sequiturs.

What I was asking is whether you can think of a structure that scales up without collapsing. Neither of your examples, possibly barring the universe as a whole, achieves that.
Maybe that is an overly strong requirement, but I just don't see a civilization rebuilding itself from scratch every time they need to add another building or something. And even if they do, the incentives would be to keep the structure as close to the brink of collapse as possible, which isn't particularly stable either.

I can't imagine why you think they would need to do that. They would build their civilisation in such a way that it never reached the critical mass or density that might cause it to collapse.

Humans have always been fascinated with building taller and taller structures. There have been a few mistakes, but in general people know the limits of what they can build with their technology. There hasn't been a steady history of people consistently building towers that cannot possible stay up.

(Also, different cultures have shared their building technology rather than simply competing with one another to build taller buildings.)

Yeah, I see where you're coming from. You assume civilizations use stars as they are as opposed to treating them as resources. I disagree with that.
Once a civilization gets hold of controlled nuclear fusion, stars already become obsolete. And that's far from the most efficient/advanced reactor theoretically possible. So it's much more likely advanced civilizations will disassemble stars and store them in some stable state as fuel, which is where the logic of my article comes in.

Even if your assumption were correct, any society that was smart enough to extract the hydrogen from stars and store it for later fusion is not going to be silly enough to let it collapse into a black hole. It would collapse into a star before that happened, rather defeating the object.

Similarly, an agent who aims to increase his freedom of action will eventually have all of it, so it doesn't matter what other agents do because their freedom of action is too small in comparison, and thus their decisions don't affect what happens to the civilization.

Yet more unrealistic assumptions. Have you studied how ecosystems work? They don't become dominated by a single species or organism that consumes all the resources.

Then why did you cite it? I will not read your article. You have to present your argument here. So far it has failed badly, so formal questions for you to answer:
Explain why an intelligent civilization or individual would be ignorant enough to build any structure that would collapse to a neutron star (a precursor to a black hole), FunBotan?
Explain why an intelligent civilization or individual would be ignorant enough to build any structure that would collapse to a black hole, FunBotan?
Especially after they probably have the example of a collapse to a neutron star!

We would not be that ignorant. A large faction of our population would not be that ignorant (they at least know that black holes can be created by piling matter up in 1 place!).

Something else for you to consider:
Just piling matter up (your "spherical structure") until it collapses to a neutron star and then a black hole or directly to a black hole requires stellar masses. Those civilizations are either dismantling some stars and shipping them to their home system or dismantling hundreds of planets and shipping them to their home system. These are activities that we should be able to detect.

N.B. We cannot create a black hole by piling up all of the matter in the Solar System. What we would get is a 0.14% heavier Sun. The Tolman–Oppenheimer–Volkoff limit needs to be exceeded (> 2 solar masses). And that assumes there is no explosion during the formation of the black hole. Normally a star has to have 15 to 20 solar masses to form a black hole!

Yet more unrealistic assumptions. Have you studied how ecosystems work? They don't become dominated by a single species or organism that consumes all the resources.

I don't know how I'm supposed to explain anything if I can't even use analogies.

Originally Posted by Reality Check

Then why did you cite it? I will not read your article. You have to present your argument here. So far it has failed badly, so formal questions for you to answer:
Explain why an intelligent civilization or individual would be ignorant enough to build any structure that would collapse to a neutron star (a precursor to a black hole), FunBotan?
Explain why an intelligent civilization or individual would be ignorant enough to build any structure that would collapse to a black hole, FunBotan?
Especially after they probably have the example of a collapse to a neutron star!

We would not be that ignorant. A large faction of our population would not be that ignorant (they at least know that black holes can be created by piling matter up in 1 place!).

Something else for you to consider:
Just piling matter up (your "spherical structure") until it collapses to a neutron star and then a black hole or directly to a black hole requires stellar masses. Those civilizations are either dismantling some stars and shipping them to their home system or dismantling hundreds of planets and shipping them to their home system. These are activities that we should be able to detect.

N.B. We cannot create a black hole by piling up all of the matter in the Solar System. What we would get is a 0.14% heavier Sun. The Tolman–Oppenheimer–Volkoff limit needs to be exceeded (> 2 solar masses). And that assumes there is no explosion during the formation of the black hole. Normally a star has to have 15 to 20 solar masses to form a black hole!

I never said anyone is going to "Just piling matter up". Of course there will be some fine structure that prevents matter from collapsing into a neutron star. But there's just no structure that can prevent a collapse into a black hole.
And of course I understand this would require gathering matter from many star systems, maybe thousands, maybe millions.
Neither of these questions really matter. I'm not laying out detailed plans for far future interstellar civilizations, I only need to determine what is that they can't possibly do.

Yeah, I see where you're coming from. You assume civilizations use stars as they are as opposed to treating them as resources. I disagree with that.

On a long enough time scale sure I see what you mean, yes eventually we would be able to disassemble stars and us them as something akin to fuel storage devices, or something of that sort. The key word being eventually. By the time we get to the point that we can disassemble stars at our will we will have long spread out to the stars to the point that, as I said before, even loosing our home star system to a terrible accident will not wipe out the entire species, and thus it's not a solution to the Fermi Paradox.

Once a civilization gets hold of controlled nuclear fusion, stars already become obsolete.

Not instantly. Stars are a HUGE source of free, constant energy. Even after we have easily mastered controlled fusion the sun will still be a valuable resource for a long time to come. So again we get the situation were yes, eventually we won't need to use stars anymore but not until long after we've spread out into the galaxy. You are correct that we won't exclusively need stars at this point, but you are wrong that we will abandon the use of stars entirely (at least not for an extremely long time).

And that's far from the most efficient/advanced reactor theoretically possible. So it's much more likely advanced civilizations will disassemble stars and store them in some stable state as fuel, which is where the logic of my article comes in.

And I agree with that, I just disagree that this can happen so rapidly that we will skip the Dyson Swarm phase of our civilization entirely and go straight from "barely able to travel between planets" to "building a black hole so enormous it will consume our solar system", which is what would be needed for this to solve the Fermi Paradox.

Well, this is the same thing as with life. Although there might be organisms that do not reproduce, they will eventually be overwhelmed by those who do, so it's completely fair to include the ability to reproduce into the definition of an organism even if it isn't necessarily true for each and every specimen.
Similarly, an agent who aims to increase his freedom of action will eventually have all of it, so it doesn't matter what other agents do because their freedom of action is too small in comparison, and thus their decisions don't affect what happens to the civilization.

Fair enough.

Also, I would be interested to hear your thoughts to these 2 points I brought up before:

Proposition 3: That individual will be incentivized to secure storage of their resources by centralizing it in one spherical structure.

Why only one spherical volume and not many? If you have colonies in star systems that span the galaxy, would it really make sense to force the colonies on the outer edges to travel 50,000 light years to the center of the galaxy to get their resources, rather then keeping it in a smaller storage structure much closer to where they need it?

Proposition 4: This structure will, in the limit, collapse into a black hole.

Why? This is the only proposition that I flat out disagree with, as I really don't understand why you would conclude this. Dyson Swarms for instance are not in danger of collapsing into a black hole, the habitats would all be in stable orbits FAR outside the Schwarzschild radius of the solar system. How could a Dyson Swarm collapse into a black hole?

We would not be that ignorant. We know that neutron stars and black holes exist. We know physics and engineering. We know that if a structure were dense enough it will collapse probably to a neutron star and then if we keep asddig matter to a balck hole.

Of course there will be some fine structure that prevents matter from collapsing into a neutron star. But there's just no structure that can prevent a collapse into a black hole.

That assertion is physically wrong, FunBotan. Any structure that prevents matter prevents matter from collapsing into a neutron star will never collapse to a black hole.Degenerate matter
A structure made of normal matter will not collapse to the material of a neutron star (neutronium) until its components are so dense that electrons are pushed into protons to make the neutrons. That is what neutron stars are named after. A structure made of neutronium will not collapse into a black hole until neutron degeneracy pressure is overcome (more matter added, more density).

This is a black hole. Black holes form when the mass of an object (star or mega structure) is inside the Schwarzschild radius (the event horizon).

For a planet in orbit around a star, your hypothetical civilization keeps adding matter until the planet collapses to a neutron star and kills the civilization. If they are intelligent, they will not be there when the neutron star forms! They can come back and keep adding matter until a back hole forms. Once again, an intelligent civilization would not be there when the black hole forms or they will be killed.

Consider a Dyson sphere that is 1 AU in radius where all of the matter is in orbit around a star. We need a really ignorant civilization that keeps adding mass to that sphere. Eventually the matter in the sphere will collapse to neutronium. AFAIK, that is so unlikely an act that no one has worked out how to do it, what would happen, or even presented it as science fiction! So we have to use the example of a neutron star to set lower limits to the mass of this structure which is ~1.4 solar masses. The actual mass will be much larger. Now we have a sphere of neutronium and a civilization actually stupid enough to keep adding mass to the sphere until it becomes a black hole. Remember that all of this matter is in orbit. It will not actually collapse to a central mass. So we look up how much mass it would take to create a black hole with a radius of 1 AU. We instantly know that this sphere has more than 4 million solar masses because Sagittarius A* has a radius of less than that of the orbit of Mercury. Schwarzschild Radius Calculator gives 50,641,975 Suns for a radius of 1 AU.

Any Dyson sphere your hypothetical civilization builds will not be a black hole until it has a mass of tens of millions of Suns !

For a Dyson swarm, your hypothetical civilization just keeps on adding more artefacts to the swarm all of which are normal matter. None become neutron stars. None become black holes. If they could somehow pack the artefacts close enough to get enough of their mass within a Schwarzschild radius, we are back to a mass of tens of millions of Suns for a 1 AU radius.

Sorry for the delay, apparently my internet cable had burnt in a fire.

Originally Posted by Dave241

On a long enough time scale sure I see what you mean, yes eventually we would be able to disassemble stars and us them as something akin to fuel storage devices, or something of that sort. The key word being eventually. By the time we get to the point that we can disassemble stars at our will we will have long spread out to the stars to the point that, as I said before, even loosing our home star system to a terrible accident will not wipe out the entire species, and thus it's not a solution to the Fermi Paradox.

Not instantly. Stars are a HUGE source of free, constant energy. Even after we have easily mastered controlled fusion the sun will still be a valuable resource for a long time to come. So again we get the situation were yes, eventually we won't need to use stars anymore but not until long after we've spread out into the galaxy. You are correct that we won't exclusively need stars at this point, but you are wrong that we will abandon the use of stars entirely (at least not for an extremely long time).

And I agree with that, I just disagree that this can happen so rapidly that we will skip the Dyson Swarm phase of our civilization entirely and go straight from "barely able to travel between planets" to "building a black hole so enormous it will consume our solar system", which is what would be needed for this to solve the Fermi Paradox.

Fair enough.

Also, I would be interested to hear your thoughts to these 2 points I brought up before:

I actually don't disagree with you on any point in principle. The only thing I think you misunderstand is scale.
Our ability to detect aliens is predicated on the scale of their civilization. Limiting this scale is enough of a solution to at least the Dyson dilemma, if not the whole Fermi paradox. It doesn't matter if some members of a species survive the collapse, and it doesn't matter how far they spread, detecting them is not going to be likely.

Originally Posted by Reality Check

That assertion is physically wrong, FunBotan. Any structure that prevents matter prevents matter from collapsing into a neutron star will never collapse to a black hole.

Counterexample: a structure consisting of multiple objects of subcritical mass orbiting each other. As long as the structure is stabilized, the objects won't collide and won't collapse on their own. But if you add enough of them, their collective mass will collapse the structure as a whole straight into a black hole. Now apply that to a more realistic example of a Dyson swarm.

Counterexample: a structure consisting of multiple objects of subcritical mass orbiting each other. As long as the structure is stabilized, the objects won't collide and won't collapse on their own. But if you add enough of them, their collective mass will collapse the structure as a whole straight into a black hole.

And no intelligent individual or society is going to do that. So you contradict your own assumptions.

I have a clear explanation in quite specific terms right here, you just don't want to read it.

I have read it.

If you are able to discuss the thing in its own terms, you should do that. Analogies are a good starting point for beginners, but everyone here is well past that point already. Just discuss the thing itself.

Counterexample: a structure consisting of multiple objects of subcritical mass orbiting each other. As long as the structure is stabilized, the objects won't collide and won't collapse on their own. But if you add enough of them, their collective mass will collapse the structure as a whole straight into a black hole. Now apply that to a more realistic example of a Dyson swarm.

A physically invalid "counterexample". FunBotan.

A good thing to do before presenting an against the mainstream argument is to learn the mainstream physics. Mainstream physics states that objects in orbit do not suddenly collapse into a central mass due to any "collective" mass. Classically this never happens. GR states that orbits are unstable due to energy radiated by gravitational waves. That takes billions of years for normal objects such as Dyson swarm objects or planets. The detailed dynamics of a Dyson swarm are different. There will be perturbations in an artefact's orbit due to the other artefacts. An intelligent civilization will build mechanisms to fix these perturbations and keep the Dyson swarm stable. No artifacts colliding. No artifacts escaping the swarm. No chance of the artefacts collapsing into a mass that may be a black hole.

An analogy: We are intelligent. We design highways and roads that have intersections. We design these intersections to minimize the chances of collisions. You are proposing that it is intelligent to ignore that collisions can happen at intersections when it is obviously not intelligent.

The Milky Way has a collective mass of ~1012 solar masses and is not a black hole.
There are multi-star stellar systems with a high collective mass and they are not black holes.
There are black holes in binary (or higher?) systems where the stars have not collapsed to a single black hole.

You missed a crucial physical point in my post: Schwarzschild Radius Calculator gives 50,641,975 Suns for a radius of 1 AU.. In order for any structure 1 AU in radius to form a black hole, it has to have a mass of 50,641,975 Suns!
Start with a Dyson swarm with 1 artefact in orbit around a star at a distance of ~1 AU. You have to keep adding artefacts inside that orbit until there are over 50 million solar masses. That has enormous physical difficulties.

I actually don't disagree with you on any point in principle. The only thing I think you misunderstand is scale.
Our ability to detect aliens is predicated on the scale of their civilization. Limiting this scale is enough of a solution to at least the Dyson dilemma, if not the whole Fermi paradox. It doesn't matter if some members of a species survive the collapse, and it doesn't matter how far they spread, detecting them is not going to be likely.

You also have to take into account the possibility that even if there is a collapse, that we would detect them before the collapse. If they are able to gather all these stars together to create their doom, why wouldn't we be able to detect them doing it?

Here's another counter argument; if any 'intelligent' civilisation was stupid enough to build a structure dense enough to collapse into a black hole, this collapse would emit as much energy as a supernova. The light from this event would travel across the universe at the speed of light, and act as a warning to all the other civilisations that are smart enough to build telescopes. This burst of light would warn all the other civilisations that see it that building dense structures is inadvisable, and a fraction of those civilisations would be smart enough to avoid such an action.

Civilisations with telescopes have an opportunity to observe each other's mistakes.

Once a civilization gets hold of controlled nuclear fusion, stars already become obsolete. And that's far from the most efficient/advanced reactor theoretically possible. So it's much more likely advanced civilizations will disassemble stars and store them in some stable state as fuel, which is where the logic of my article comes in.

Oh, I agree with that. Disassembling stars and burning the fuel in a controlled way is much more sensible. Here's an image I've made of a disassembled star, reconfigured as a series of dynamically controlled rings; in practice there would be many more rings, and the fusion sources would be smaller, but this is just an indication of how things might work.Matrioshka Hypernode

From a distance this structure would look something like a tiny globular cluster - and it could be expanded indefinitely without ever collapsing into a black hole. Note that globular clusters themselves are large, relatively dense objects, and they persist for billions of years with no tendency to collapse. I think a suitably advanced galactic civilisation could convert its home galaxy into a giant-sized globular cluster, and live there in reasonable security for many billions of years. Why would they do such a thing? Mainly to reduce signal latency between the different elements of the civilisation. An entire galaxy could be collapsed into a cluster about fifty light years across without any danger of collapsing into a black hole. A message lag of 50 years would be preferable to one of 100 thousand years.

You cannot start with an assumption of an intelligent civilization and turn them into a stupid civilization..

I think you're still misunderstanding my first premise. I never said there's such a thing as an intelligent civilization. I defined a civilisation as a set of agents, where every individual agent is intelligent. My primary objective is prove that this setup leads to the whole civilization not behaving intelligently.

Originally Posted by Jens

You also have to take into account the possibility that even if there is a collapse, that we would detect them before the collapse. If they are able to gather all these stars together to create their doom, why wouldn't we be able to detect them doing it?

Yes, that is a valid point. But again, the question is whether we're looking for the right things. Seeing whole stars moving is very unlikely since they will probably be disassembled and moved in small chunks. We might be able to catch such process taking place, or maybe detect the waste heat.

Originally Posted by eburacum45

Here's another counter argument; if any 'intelligent' civilisation was stupid enough to build a structure dense enough to collapse into a black hole, this collapse would emit as much energy as a supernova. The light from this event would travel across the universe at the speed of light, and act as a warning to all the other civilisations that are smart enough to build telescopes. This burst of light would warn all the other civilisations that see it that building dense structures is inadvisable, and a fraction of those civilisations would be smart enough to avoid such an action.
Civilisations with telescopes have an opportunity to observe each other's mistakes.

There is no reason for a black hole collapse in the general case to emit any radiation. Don't just assume any structure on the scale of a star will behave like a star.
Also, as I note explicitly in the article and here before, awareness of this threat isn't a defence against it; otherwise it wouldn't be a solution to the Fermi paradox.

Originally Posted by eburacum45

From a distance this structure would look something like a tiny globular cluster - and it could be expanded indefinitely without ever collapsing into a black hole. Note that globular clusters themselves are large, relatively dense objects, and they persist for billions of years with no tendency to collapse. I think a suitably advanced galactic civilisation could convert its home galaxy into a giant-sized globular cluster, and live there in reasonable security for many billions of years. Why would they do such a thing? Mainly to reduce signal latency between the different elements of the civilisation. An entire galaxy could be collapsed into a cluster about fifty light years across without any danger of collapsing into a black hole. A message lag of 50 years would be preferable to one of 100 thousand years.

Using an idea of something that is impossible is again an assumption and your proposition fails. You have shown too many assumptions in your discussion, this being only one of them. And as many have post you fail.

This looks like the fallacy of begging the question.
If the civilisation is aware of the threat, then why wouldn't they take action to avoid it?
I can't see how. Eburacum45 is pointing out that collapse to a black hole is easily avoided, rather than the inevitability that you claim.

C. But if the collapse is so easy to predict, and
there is a sentient entity in control, that entity will
not allow it.
The key point is that no agent is actually in
control. Rather, the established system is in control
of the agents. A more intuitive example of such
a situation is the Prisoners’ dilemma [10]. The
same description can be applied to governments
accumulating advanced weapons that can never
be used, bankers’ behaviour preceding a financial
crash and the global response to climate change.
Generally speaking, there is no basis to claim
that systems consisting of rational agents also act
rationally.

F. If agents are meant to maximize their future
freedom of action (2.2), why wouldn’t they factor
in the probability of a collapse?
Even if they do, this should not affect their
behavior. If they choose to suspend growth for
safety, another agent will exploit that, as explained
in 3.5. The risk will grow with time no matter
what they do. And, given the time scale that an
interstellar civilization needs for development, that
risk accumulates to a near certainty of collapse.

I think you're still misunderstanding my first premise. I never said there's such a thing as an intelligent civilization. I defined a civilisation as a set of agents, where every individual agent is intelligent.

It does not matter whether it is an intelligent civilization, "agents" or even cats (), FunBotan.

IF03: Support your "There is no reason for a black hole collapse in the general case to emit any radiation" assertion with sources from the scientific literature, FunBotan.
This may be impossible because the collapse of normal matter into a black hole is a gravitational collapse that heats that matter and will generate radiation. No radiation and your "agents" should still be there. They would left the "collapsing" structure and be in orbit around a black hole!
On the other hand just adding mass inside the structure (~50 million stars for a 1 AU wide one) will form a black hole without radiation.

The problem with that statement is that this whole thread starts from a positive claim by you, that you have solved the paradox, and so unless you can show all the statements that lead to that conclusion to be true, then you no longer have a solution but a "this is one possibility, if my assumptions all turn out to be true."

Yes, that is a valid point. But again, the question is whether we're looking for the right things. Seeing whole stars moving is very unlikely since they will probably be disassembled and moved in small chunks. We might be able to catch such process taking place, or maybe detect the waste heat.

Somebody else mentioned that we definitely would notice a star being moved, because even if it disappeared over a period of decades, it would disappear from the star charts and stars just don't do that.

But in any case, the more important point is that if you recognize this possibility (that we might be able to see it happening if we looked in the right place), then it also means that you no longer have a solution to the paradox but only a possible solution.

C. You have a set of intelligent agents and a "system" that you assert is not intelligent. That is at least 1 assumption in an thread titled "Solving the Fermi paradox without assumptions"!
All aliens will not have human politics or psychology. A claim without evidence is not science.

F. A set of intelligent agents that want to maximize future options will not include certain extinction as an option!
You are claiming that formation of a black hole is certain extinction. Every agent in your set of agents will know that. Your system will know this.

Yes, that is a valid point. But again, the question is whether we're looking for the right things. Seeing whole stars moving is very unlikely since they will probably be disassembled and moved in small chunks. We might be able to catch such process taking place, or maybe detect the waste heat.

Expanding on Jens reply that we would see these stars vanishing from star charts. We have been recording the positions of stars for thousands of years. People would have noticed and probably recorded prominent, local stars vanishing. The Wikipedia star catalogue lists many catalogues. The still operating Gaia spacecraft has 2 data releases so far

The second data release (DR2), which occurred on 25 April 2018,[9][66] is based on 22 months of observations made between 25 July 2014 and 23 May 2016. It includes positions, parallaxes and proper motions for about 1.3 billion stars and positions of an additional 300 million stars, red and blue photometric data for about 1.1 billion stars and single colour photometry for an additional 400 million stars, and median radial velocities for about 7 million stars between magnitude 4 and 13.

We would very probably see maybe tens of millions of stars being disassembled by a set of ignorant agents to build a structure that forms a black hole which should not destroy the agents.

But in any case, the more important point is that if you recognize this possibility (that we might be able to see it happening if we looked in the right place), then it also means that you no longer have a solution to the paradox but only a possible solution.

I'm still intrigued. Why do you think that a civilisation would necessarily build a structure that would collapse into a black hole, rather than expand that structure as necessary if they increase its mass? Is your argument that they would not be able to expand the structure for some reason? I am prepared to accept that if (and only if) you talk us through the steps that make it inevitable.

After all, it should be possible to build a structure that includes all the available mass in the universe without allowing it to collapse into a black hole, while still obeying the restriction that the structure is denser than the current state of the universe. Or do you disagree with that?